In chemical terms, salt is a simple compound: one atom of sodium attached to one atom of chlorine. Biologically, it appears to be sodium that is most vital to life, and has been so since the first one-celled organisms arose in the salty waters of our planet's early seas.
When multicellular organisms evolved and crawled up the beaches to dry land, they had to take the seawater with them in the blood and other body fluids. The mineral content of human blood plasma today is still much like that of the seas of the Precambrian era in which life arose.
But salt is often scarce beyond reach of the oceans. And the ancestors of man for at least 25 million of the last 30 million years were almost certainly vegetarians, and therefore got little salt in their diets because most plants store little salt.
To compensate for the scarcity of a substance vital to life, the brains of our ancestors and those of other mammals developed powerful strategies for getting and keeping salt. Inborn, Not Learned
Many animal species, evidently including humans, have an innate hunger for salt that the brain brings into play as soon as special populations of brain cells register the fact that the body does not have as much sodium as it needs. This response is inborn, not learned, in Dr. Denton's view. In experiments, young animals exhibit a hunger for salt the first time their bodies become deficient in sodium.
''That is, salt appetite emerges spontaneously on the animal's first experience of sodium deficiency,'' said Dr. Denton. ''It is not an instance of the animal learning by trial and error that salt ingestion relieves the sensations induced by deficiency.''

yes, this pretty much explains it. salt is essential for almost all land animals to regulate the water in their body and transmission of nerve impulses (Na atoms).

today, where salt is very common and easily accessible, you body still treats it as a rarity. because it was a rarity thousands of years ago. we might have achieved great lengths with technology but our bodies are still what they were 30,000 years ago. same with sugar and fat. your body wants to store as much as possible for it still thinks that you will starve until the next hunt.

yes, this pretty much explains it. salt is essential for almost all land animals to regulate the water in their body and transmission of nerve impulses (Na atoms).

today, where salt is very common and easily accessible, you body still treats it as a rarity. because it was a rarity thousands of years ago. we might have achieved great lengths with technology but our bodies are still what they were 30,000 years ago. same with sugar and fat. your body wants to store as much as possible for it still thinks that you will starve until the next hunt.

i mean if a body gets used to constant intake of sugar, salt and fat it will *demand* to keep it up. when one starts a diet then that intake is reduced, i.e body's balance is upset (the body has no idea that it's bad for it ). that's why people get a bit angry/depressed when they start a diet. only when the body understands that this amount of sugar, salt, fat intake is the new regime then it accepts it. could take a long time, though.